1. Field of the Invention
This invention relates to the preparation and administration of a product into a living organism (e.g. the human body), and more particularly to an apparatus for automatically and safely delivering the product.
2. Description of Related Art
Previously, various devices have been developed for the delivery of medications into and through the skin of living organisms. These devices include syringes in which a liquid drug solution is delivered through the skin of a user from a syringe chamber by movement of a syringe plunger to move the drug solution from a syringe chamber through a syringe needle inserted under the skin. The drug solution is generally in liquid form, and can be a mixture of the drug (e.g. powdered, lyophilized, concentrated liquid) and a diluent (e.g. dextrose solution, saline solution, water).
It is well known that many people are apprehensive about receiving an injection from a needle. This problem is even more significant for those who must administer their own medication. It is known that needle phobia can be minimized by hiding the needle before, during and after delivery. It is therefore preferable that the person who receives the drug should not see the needle, which often triggers the fear of needle insertion.
It is also preferable for the needle to be protected before and after delivery of the drug. While a needle can be protected with a removable cap, it is preferable for the needle to be secured within the delivery device before the needle is inserted through the patient's skin and after the needle is shielded. Preferably the needle is enclosed in the device after use and locked into final position after injection.
The needle insertion is assisted by the user or caregiver or is automatic, whilst its shielding is automatic, so that the user does not prematurely expose the needle for injection or have to guess when delivery is completed.
It is also preferable for such a device to provide indications for assisting in the correct use of the automatic injector. Indications could be visual, audible or tactile and are provided at the start or completion of any stage of system use.
A user or patient could be injured if an injection device were activated prematurely. Generally, such a device projects its needle from the end of a barrel and ejects the dose. Such actions can cause injury if the needle pierces another person or is injected into an undesired area of the patient (e.g., an eye). Accordingly, it is advantageous if the needle is in a safe location before and after use to prevent accidental injury or contamination.
It is further desirable to have a simple, reliable system that facilitates safe preparation and delivery of a drug. Dosage amounts may vary from one patient to another. At present, there is no easy way for a patient to self-administer a dosage of drug via an automatic injection system where the dosage amount may be easily changed prior to delivery and easily delivered. Moreover, there is a need to further improve the ability of the user to minimize residual drug in the container or system. Also, there is a need to enable the user to eliminate any air bubbles that may be trapped in the drug container prior to use.
It is also desirable to provide a delivery system where the dosage for delivery is easily viewed by the patient prior and after use. The user's inability to see the dosage form prior to use creates a significant sense of unease in the user in that the user wants to ensure that the proper dosage is in the system and ready for delivery. More importantly, the users inability to see the dosage form prior to use leaves the user concerned that the dosage may be faulty, or, for example, have foreign particles trapped and if present, may result in injury or harm to the user.
The user's inability to view the dosage being delivered and the end of delivery leaves the user with a level of uncertainty as to the amount delivered and the delivery being completed. Thus, it is extremely important to the user's peace of mind to provide an area in which to view the dosage prior to and after delivery. As will be discussed in detail later, the injection device of the present application provides this opportunity.
Further, it is desirable to provide a delivery system that is easy to use at a low cost. Moreover, it is desirable to provide a system that is easy to integrate with the drug container, thereby providing flexibility in meeting the requirements of different drug containers like pre-filled syringes/cartridges. For example, it is important to accommodate standard cartridges with a needle cover including a rigid plastic cover. Moreover, it is desirable to have a system that can accommodate cartridges filled on standard filling lines. It is desirable to provide a system characterized by a small number of components indicating low product costs.
The following are exemplary existing automatic injectors.
U.S. Pat. Nos. 5,114,406 (Gabriel, et al.); and 6,544,234 (Gabriel) disclose a plunger which is telescopically received within a tubular element causing the needle penetration, drug delivery and securing the needle. Beside it being a telescope type mechanism the system is using two springs and the detection of end of delivery is controlled by packaging parts and not by the cartridge only.
U.S. Pat. No. 5,599,309 (Marshall, et al.) discloses an injector having a drive member held in a rearward primed position by a detent provided in the body of the device. When the device is applied to a patients skin and a rear end cap is pressed forwardly, the forward ends of ribs wedge tongues inward (or pivot) until they clear the detents formed by the forward ends of the slots. A coil spring shoots a cylinder forward for injection and delivery. This invention is involving the packaging parts in order to detect end of delivery and is using two springs—one to penetrate and deliver and the second to shield.
U.S. Pat. No. 6,159,181 (Crossman, et al.) and U.S. Patent Publication Nos. 2003/0093036 and 2003/0105430 (Crossman, et al.) are mechanisms to deliver drugs in a parenteral method and to shield the penetrating needle after use. Both mechanisms use double springs and do not use the cartridge to detect the end of delivery. In 2003/0093036 (Crossman, et al.) the user is expected to manually trigger the needle shield and to decide when to do that. The evolution between these two applications is in making the device simpler and more accurate. Nevertheless, the basic principles remain the same.
The following exemplary patents are mentioned as they relate to needle retraction mechanisms. Several disclose axially-aligned spring-driven needle extenders and retractors. These include U.S. Pat. Nos. 5,779,677 (Frezza); 6,210,369 (Wilmot, et al); 5,391,151 (Wilmot); 5,637,094 (Stewart, Jr., et al.) and U.S. Patent Publication No. 2001/0005781 (Bergens et al.). In all of these references, the function is served by a set of axially-positioned springs; in some, two springs are in use and in others, such as Stewart's and Bergens, even three springs are used. None of the references includes a mechanism for cartridge-shape detection.
In U.S. Patent Publication No. 20030105430 (Lavi, et al.), the functions are served by a mechanism of ten parts, including two springs. The mechanism performs a combination of slide and rotate move, the end of delivery is detected by the packaging parts and not by the shape of the cartridge. The design is characterized by high complexity and costs.
U.S. Pat. No. 6,743,203 (Pickhard) discloses a device for automatically injecting liquids and comprises an axially-divided housing wherein the parts can be removably assembled. The design employs a cartridge with a separate needle assembly and three springs resulting in high complexity.